This invention relates to a system for providing a constant supply of power.
The need for uninterruptable power sources is especially acute in the computer field since an interruption of power may result in the loss of information stored in memory and thus the loss of many hours or days computing effort. Although computer memories have been developed which can maintain stored information even with an interruption of power, such memories are still quite expensive and not yet in widespread use. There is also a need for secure power sources in hospitals, medical emergency facilities, and the like.
There are a number of arrangements for protecting against power interruption or failure, ranging from use of an array of batteries to back up the commercial power source to provision of an entirely separate power generating plant. Some previously proposed systems for providing uninterrupted power are disclosed in U.S. Pat. Nos. 3,345,517, 3,558,901, 3,675,112, 2,194,822, 2,783,393, 2,917,635, 3,178,632, 3,221,172, 3,283,165, 3,477,013, and 3,609,426. These and other prior art systems are typically expensive, not entirely fail-safe, or rough in making the transition between the primary power source and the stand-by source. Since the need for emergency power generally arises only infrequently, it would be desirable that such need could be satisfied with a low cost, reliable and efficient backup power system.